Process of making carbon dioxid and solid sodium sulfite.



H. HOWARD. PROCESS OF MAKING CARBON DIOXID AND SOLID SODIUM SULFITE.

APPLiCATION FILED MAY 6. 19 13.

Lmfiwa Patented m. 21, 1915.

' and is an improvement ill it i t t Till nan nowann, or nos'ron, inassacnusn'rrs.

PROCESS 01E MAKING CA 1 a DIOID AND SOLID SODIUM SULFTTE.

specification of Letters Patent.

Patented 1D@ l3h 211i, ZWJW,

Application filed March 6, 1913. serial Ito. 752,281.

I To all whom it may concern Be it known that I, HENRY HOWARD, a citizen of the United States, residin vat Boston, in the county of Suffolk and tate of Massachusetts, have invented certain new and useful Improvements in Processes of Making Carbon Dioxid and Solid Sodmm Sulfite, of which the following is a specification.

This invention relates to a process of making carbon dioxid and solid sodlum sulfite,

ugon the process described in my Patent 0. 651,569, dated June 12, 1900.

The object of my invention is to make pure carbon dioxid from a suitable carbonate, such as sodium mono-carbonate, sesquicarbonate, or bicarbonate, or a mixture of them, or from any other alkaline or alkaline earth carbonate, under conditions which will give a solid sulfite salt that may be utilized for other purposes, such as the manufacutre of bisulfite of sodium, etc.

In carrying out this process a solid carbonate of sodium, or of any other suitable base, is added to a strong, preferably saturated, solution of sodium bisulfite, or a bisulfite of the base in the carbonate, in such quantities that carbon dioxid is liberated and a neutral sulfite in the solid form is produced by the reaction between them, as indicated by the following reactions:

with solid bicarbonate of sodium,

This reaction, with a solid sodium carbonate, produces neutral sodium sulfite in such excess that it also separates from the solution as a finely divided solid sodium sulfite suspended in 'a saturated solution of sodium sulfite, and may be used in making solid sodium bisulfite according to the process described in my application Serial No. 744,67 5, filed January 28, 1913, which matured into Patent 1,084,436, dated Jan. 13, 1914. During the operation, it is preferable to heat the mixture to drive out all the carbon dioxid, otherwise some will remain dissolved in the solution of sodium sulfite, and be lost.

In the accompanying drawing, which illustrates a plant for carrying out the process,a tank 1, provided with a valved outlet 2, supplies a strong solution of bisulfite to the bottom of the reaction tank 3; a suitable carbonate is added to tank3 through the air-lock manhole 4, and is kept in susso pension in the bisu'lfite solution by the stirrer 5; the mixture of bisulfite and carbonate may be heated by the heating coil 6, if desired. The gas evolved j by the reaction passes out through the "IF-outlet pipe 7, and t5 when the reaction is over, the resulting mass of solid sulfite of sodium and its saturated solution are removed through the bottom outlet 8. The carbon dioxid may be used as generated, or may be purified by passing It into a suitable scrubber 10 through a perforated pipe 9. The scrubber preferably contains a solution of carbonate or bicarbonate of sodium 11', which absorbs any traces of sulfur-dioxid gas that may come from the bisulfite in tank 3. A pump 12 exhausts the dioxid from the reaction tank 3 direct by opening valve 13 and closing valves 14 and 15; or through the scrubber by closing valve 13 and opening valves 14 and 15. 8%

I have shown the admission of bisulfite solution to the bottom of the reaction tank 3 for the reason that bisulfites are not very stable in solution; they tend to decompose on slight heating, and on agitation; by this M process, the bisulfite reacts upon the lower strata of carbonate, the evolved gas passing through the upper solution and in contact with more carbonate whereby any sulfur dioxid will be absorbed, liberating carbon W dioxid and forming neutral sulfite. The agitation of the mass facilitates the reaction.

In my prior Patent No. 651,569, above referred to, it is stated that dry sodium carbonate may be used as a source of carbon dioxid, the bisulfite solution to which it is added having sufficient Water to dissolve it. According to the present process, the same reaction is employed but the Water is present in restricted proportion to the reacting bodies (bisulfite and carbonate) with the result that a portion of the neutral sulfite which is formed is obtained directly in solid form, the output of product from an apparatus of given size being correspondingly increased. The proportion of carbonate added is carefully controlled, as indicated by the foregoing equations, to avoid any excess above the amount required to yield the 1m normal sulfite, for the reason that any such excess, whether in solution or in suspenslon,

would contaminate the product ('sulfite) if intended for commercial purposes, or would involve a corresponding loss of carbon dioxid in case the sulfite is treated with burner gases for re-conversion into bisulfite in accordance with my Patent No. 1,084,436, according to which the neutral sulfite solution containing undissolved sulfite is saturatedcarbonate in excess of the amount soluble in the liquid, is claimed in my application Serial Number 62,700, filed November 22, 1915, as a division hereof.

I claim 1. The process of making pure carbon dioxid and a solid normal sulfite in a single operation, which consists in reacting u on an aqueous solution of a suitable bisu fite with a solid carbonate, the carbonate not in excess of the proportion required for the formation of normal sulfite, and the water in insuflicient proportion for the complete solution of the normal sulfite formed.

The process of makin pure carbon di- OXld and solid sodium sul te in a single operation, which consists in reacting upon an aqueous solution of sodium bisulfite with solid sodium carbonate, the carbonate not in excess of the proportion required for the formation of normal sodium sulfite, and the water in insuflicient proportion for the complete solution of the normal su'lfite formed.

In testimony whereof I afiix my signature in presence of two witnesses.

HENRY HOWARD.

Witnesses:

I. M. GRAHAM, M. V. OBRIEN. 

